Centrifugal projection spray gun head



Sept. 15, 1959 w. HEARD CENTRIFUGAL PROJECTION SPRAY GUN HEAD Filed Dec. 10, 1957 I Inventor WILL/AM 1.. HEARD Q-W Q L, Patmaent United States Patent CENTRIFUGAL PROJECTION SPRAY GUN HEAD William L. Heard, Milton, Ontario, Canada Application December 10, 1957, Serial No. 701,807

8 Claims. (Cl. 239-120) This invention relates to a centrifugal projection spray gun head of novel concept and structure embodying means for controlling the angle or width of the spray curtain.

Prior devices for projecting paint or the like by centrifugal force provide for the projection of a cone-like curtain of fine particles. In such devices the liquid to be sprayed is in principle projected as a stream rotating at high speed whereby particles thereof are caused to fly outwardly. By this means a diverging cone of particles may be formed which tends to form a ring-like deposit on a stationary article being sprayed. Such devices are therefore used for the spraying of relatively large moving sheets. Also such devices generally depend upon the utilization of air pressure to assist in breaking the liquid into small particles. Prior centrifugal spray head devices therefore do not depend solely upon centrifugal force for the breaking up of the liquid into fine particles but rather use centrifugal force as an additional force characteristic in providing a satisfactory cloud-like distribution of fine particles. Such devices are spray devices in the sense that air pressure is used in a primary sense.

Attempts to provide a device for projecting a liquid as a curtain of fine particles of relatively uniform coverage density by utilizing centrifugal force alone have been relatively unsuccessful for the reason that while centrifugal force at very high speed enables a satisfactory break-up of the liquid into fine particles, the particles are thrown outwardly tangentially from a high speed rotating unit at right angles from the axis of rotation at all points around the periphery of a spinning lip so that a disc-like projection of fine particles is achieved. Such a device is therefore useless except for the possible single application of moving it coaxially within a cylinder the inner surface of which is desired to be painted.

It is the main object of this invention to provide a liquid projecting apparatus adapted to provide a con trol-lably spray curtain and depending primarily upon the utilization of centrifugal forces as a projecting force and as the force utilized in breaking up the liquid into fine particles.

It is a further object of the invention to provide liquid projecting apparatus as set forth herein in the form of a centrifugal projector such as a' frusto-cone rotating at high speed and terminating in an outward lip from which the liquid is adapted to tangentially depart in small particles and in combination with a control frusto-cone of a form converging outwardly and containing said projecting frusto-cone therewithin on an inclined axis with respect thereto, thereby to provide an effective aperture condition whereby only a portion of the liquid projected from the said projecting frusto-cone is exposed for free passage beyond said control frusto-cone and wherein the latter serves as a return feed reservoir of non-projected liquid.

Other objects of the invention will be appreciated by a study of the following specification taken in conjunction with the accompanying drawings.

In the drawings:

Figure 1 is an underside perspective view of a centrifugal projecting spray gun head of the invention;

Figure 2 is a side elevation of the gun head of Figure 1 showing portions of the structure cut away to reveal details of construction thereof.

Referring to the drawings a bracket 10 is shown fastencd to the motor device 11 by a screw 12. The motor device 11 may be any conventional hand tool motor mechanism such as a portable hand drill apparatus of well-known form having a rotatable chuck shaft 13. A drive shaft 14 extends outwardly from the chuck 13 of motor 11 being rotatably supported in bushing 15 of arm 10, extending therebeyond to support a drive pulley 16. A downwardly depending arm 17 of bracket 10 supports the fixed bearing sleeve 18 having an angular shot 19 therein adapted to contain the adjusting arm 20. Adjusting arm 20 connects to outer race 21 of the thrust ball bearing structure 22, the inner race 23 of which is fastened to the rotatable sleeve 24- forming an integral coaxial part of the high speed outwardly diverging primary projecting frusto-cone 25 rotated by drive pulley 26 connected by the crossed belt 27 to driven pulley 16. The stationary shaft 28 restrained from rotation and supported at right angles to arm 17 by supporting arm 29 or by other equivalent structure carries a pickup scoop 30 at its inward end 31 which is stationary and embodies an inclined aperture 32 communicating by an internal duct 33 and openings 34 to the inner regions 35 of the outwardly diverging projecting frusto-cone 25. The frusto-cone 25 is adapted to rotate at high speed in the direction of the arrow Y whereby fluid therein migrates under the action of centrifuga l force for tangential projection from the lip 36 thereof to provide a disc-like sheet of particles or spray curtain 37.

Liquid is fed to the scoop 30 by means of a feed control and spray curtain control device in the form of a secondary frusto-cone structure 38. The secondary frusto-cone structure 38 is generally of a converging nature on an inclined axis 39 about the primary frusto-cone 25 and comprises a converging intermediate frusto-cone part 40 having coaxially thereabout an outer tertiary converging frusto-cone part 41 joining in a common base 42 carrying a toothed flange 43 meshing at an inclined angle with drive gear 44 on drive shaft 14. Base 42 is freely rotatable within the stationary bearing 4-5 on inclined support arm 46 fastened to the motor drive unit 11. Base 42 embodies a coaxial bore 47 adapted to accommodate a feed tube 43 therethrough for communication of liquid under pressure from a conventional fluid pump from a liquid reservoir (not shown) to the nozzle 49 of the feed tube thence to the inner regions 50 of the spray curtain. control structure 51.

In operation liquid to be projected is pumped through tube 48 into the inner region 50 of structure 51 which region may be regarded as a liquid reservoir. Since structure 51 is rotating at high speed in the direction of Y that is, preferably in the same direction as arrow Y, the incoming liquid will be thrown outwardly toward the inwardly converging walls 52 of structure 51. While the surfaces 52 converge outwardly they diverge inwardly toward the base wall surface 53 to a region 54 of a maximum diameter accessible to the aperture 32.. of the liquid pickup scoop 30. The liquid at region 54 is rotating substantially with the structure 51 at relatively high speed and therefore enters the aperture 32 with some force causing it to pass up the passages 33 and 34 into the inner regions of the diverging primary frusto-cone 25 likewise rotating at high speed. It is of interest to observe however that the axis 55 of the primary frusto-cone 25 extends substantially toward the reservoir region 54 of maximum diameter within the rotating structure 51 and proceeds therefrom at an angle with respect to the axis 39 of the structure 51 in such manner as to provide a substantial occlusion of the lip 36 of the frusto-cone 25 by the inner lip 56 of the intermediate diverging frustocone 40. By this means, only that portion of the spray curtain 37 not intersected by the intermediate lip 56 escapes to form a projecting curtain 5 7 of fine particles of liquid.

The angle of the spray curtain 57 designated as the angle A in Figure l is determined by the axial adjustment of the primary frusto-cone 25 within the feed control structure 51 by operation of adjusting handle 20 or equivalent structure. frusto-cone is moved to the position indicated in chain lines by numeral 58 that the plane of the lip 36 designated by the chain line 59 will then fall Within the lip 56 of structure 51. At this position the entire spray curtain 37 will be returned to the reservoir 54. As the primary frusto-cone is moved outwardly, less of the spray curtain is occluded by the feed control lip 56 of structure 51 whereby an increase of the angle A of Figure 1 to a maximum is limited only by the geometry of the structure.

It has been found that some liquid will always migrate outwardly over the inner Walls 52 of the control frustocone structure 51 and will migrate outwardly over the control lip 56. The invention therefore contemplates the provision of inwardly diverging return passages 60 communicating from the juncture 61 of the intermediate and outer frusto-cones 40 and 38 to the inner surfaces 52 and hence the reservoir 54. It has been established as a result of many tests that the passages 60 and the outer frusto-cone 40 are essential elements of the combination for avoiding the unnecessary loss of some liquids having high migration characteristics. No explanation is given here concerning the migration of liquids in a direction apparently counter to centrifugal forces other than the fact that experience shows that this phenomena does ocour to a degree requiring that it be taken into account to render the device practical for the handling of many liquids.

In a general sense the invention concerns a liquid projecting gun head suitable for paint spraying or the like, provided in the form of a hollow primary cone of a frustroconical geometry which, at the small or apex end, provides an inlet opening defining the inner terminus of the conical side walls thereof. The side walls diverge outwardly from the inlet opening to terminate at a rim forming a liquid projecting lip from which liquid is adapted to depart tangentially upon rotation of the primary frusto-cone. The primary frusto-cone is rotated at suitable speed to provide motion of the liquid outwardly along the inner surfaces of the diverging walls, effecting projection of particles of the liquid from the rim of the liquid projecting lip to provide a spray curtain of liquid tangentially thereabout. A hollow control frusto-cone structure substantially encloses the primary frusto-cone in the preferred arrangement of components, extending about and being spaced therefrom. The side walls of the control frusto-cone structure converge from a relatively large diameter base toward an outward terminus defining a feed control lip for the spray curtain or control opening. Fluid may be introduced into the control frusto-cone so that upon rotation of the latter it flows toward a large diameter region adjacent the base serving as a fluid reservoir. The control frusto-cone structure is supported and rotated on a rotary axis inclined with respect to the rotary axis of the primary frusto-cone, in such manner as to provide for substantial occlusion of the spray curtain for return of the occluded liquid within the control structure to the reservoir thereof. That portion of the spray curtain not encountered by the control lip of the control structure escapes from the gun head as a spray of fine particles. The primary frusto-cone is preferably fed with liquid by a stationary scoop extending It will be seen that if the primary into the primary reservoir of the control frusto-cone. The primary frusto-cone may be adjusted along its axis to determine the degree of occlusion of the spray curtain, that is, the effective aperture provided by the geometry of the two frusto-cones for liquid to escape therefrom. The control frusto-cone structure embodies an intermediate frusto-cone part upon which the feed control lip is formed. An outer tertiary frusto-cone part is also carried by the control fnisto-cone structure and has a lesser angle of; convergence than the intermediate frusto-cone part forming a secondary reservoir therewith for liquid migrating exteriorly of the feed control lip of the intermediate frusto-cone part. Passages are provided for communicating liquid from the secondary reservoir to the primary reservoir whereby all liquid which does not escape in the non-occluded spray is returned to the primary reservoir.

The suitability of the device of the present invention for the mixing of separate liquids within the reservoir will be apparent to skilled persons. It is therefore intended that this disclosure having regard to the concepts involved should not be construed in any sense limiting the subject matter thereof other than that apparent from the scope of the following claims, having regard to the prior art.

What I claim as my invention is:

1. A liquid projecting gun head comprising, in combination: a hollow primary frusto-cone having an inlet opening defining the inward terminus of the conical side walls thereof, the latter diverging outwardly therefrom to form a liquid projecting lip; feed means for introducing liquid to the inlet opening of said primary frusto-cone; means for rotating said primary frusto-cone to discharge said liquid from the projecting lip thereof under the action of centrifugal force effectively to form a spray curtain thereabout and tangentially therefrom; a hollow control frusto-cone structure extending about and spaced from said primary frusto-cone and having side walls converging toward an outward terminus defining a feed control lip for said spray curtain; a primary fluid reservoir Within said control frusto-cone structure at a region of maximum inner diameter of the side walls thereof; and means for rotating said control frusto-cone structure on an axis inclined with respect to said primary frusto-cone to provide escape of a portion only of said spray curtain therefrom, and effecting return of the remainder of said spray curtain within said control frusto-cone structure to said primary reservoir therein.

2. A liquid projecting gun head as claimed in claim 1, in which said feed means for introducing fluid to said primary frusto-cone inlet opening comprises: means for introducing liquid into said control frusto-cone structure; and means associated with said primary frusto-cone including a scoop within said primary reservoir for deflecting fluid from said primary reservoir to the inlet opening of said primary frusto-cone.

3. A liquid projecting gun as claimed in claim 1, and primary frusto-cone axial adjustment means for axially adjusting said primary frusto-cone within said control frusto-cone structure to control the portion of said spray curtain returned by said secondary frusto-cone structure to the primary reservoir therein.

4. A liquid projecting gun as claimed in claim 1 in which the control frusto-cone structure embodies an intermediate frusto-cone part defining said control lip and an outer tertiary converging cone part having a lesser angle of convergence than said intermediate cone part and forming therewith a secondary reservoir for liquid migrating exteriorly of said feed control lip; and liquid communicating passages diverging inwardly from said secondary reservoir to said primary reservoir of said control frusto-cone structure.

5. A liquid projecting gun as claimed in claim 1, in which said means for feeding fluid to said primary frustocone inlet opening comprises: means for introducing liquid into said control frusto-cone structure; means associated with said primary frusto-cone including a scoop within said primary reservior for deflecting fluid from said primary reservoir to the inlet opening of said primary frusto-cone; and means for axially adjusting said primary frusto-cone within said control frusto-cone structure to control the portion of said spray curtain returned by said secondary frusto-cone structure to the primary reservoir therein.

6. A liquid projecting gun head as claimed in claim 1, in which said means for feeding fluid to said primary frusto-cone inlet opening comprises: means for introducing liquid into said control frusto-cone structure; means associated with said primary frusto-cone including a scoop within said primary reservoir for deflecting fluid from said primary reservoir to the inlet opening of said primary frusto-cone, said control frusto-cone structure embodying an intermediate frusto-cone part defining said control lip and an outer tertiary converging frusto-cone part having a lesser angle of convergence than said intermediate frusto-cone part and forming therewith a secondary reservoir for liquid migrating exteriorly of said feed control lip; and liquid communicating passages diverging inwardly from said secondary reservoir to said primary reservoir of said control frusto-cone structure.

7. A liquid projecting gun as claimed in claim 1, in which said means for feeding fluid to said primary frustocone inlet opening comprises: means for introducing liquid into said control frusto-cone structure; means associated with said primary frusto-cone including a scoop within said primary reservoir for deflecting fluid from said primary reservoir to the inlet opening of said primary frusto-cone; means for axially adjusting said primary frusto-cone within said control frusto-cone structure to control the portion of said spray curtain returned by said secondary frusto-cone structure to the primary reservoir therein; said control frusto-cone structure embodying an intermediate frusto-cone part defining said control lip and an outer tertiary converging frusto-cone part having a lesser angle of convergence than said intermediate frusto-cone part and forming therewith a secondary reservoir for liquid migrating exteriorly of said feed control lip; and liquid communicating passages diverging inwardly from said secondary reservoir to said primary reservoir of said control frusto-cone structure.

8. A liquid projecting gun as claimed in claim 1 in which the control frusto-cone structure embodies an intermediate frusto-cone part defining said control lip and an outer tertiary converging frusto-cone part having a lesser angle of convergence than said intermediate frustocone part and forming therewith a secondary reservoir for liquid migrating exteriorly of said feed control lip; liquid communicating passages diverging inwardly from said secondary reservoir to said primary reservoir of said control frusto-cone structure; and means for axially adjusting said primary frusto-cone Within said control frusto-cone structure to control the portion of said spray curtain returned by said secondary frusto-cone structure to the primary reservoir therein.

References Cited in the file of this patent UNITED STATES PATENTS Norris Aug. 7, 1951 FOREIGN PATENTS 

